1. Field Of The Invention
The present invention relates to an improved, liquid cooled chuck for a rotary, metal cutting tool, such as an end mill.
2. Description Of The Prior Art
There are numerous metal machining operations which employ cylindrical bits rotated at high speed to cut metal chips from a workpiece. Exemplary among such devices are end mills, shell mills, drills, routers, reams, bores, and other high speed, rotary systems which cut metal with a sharp bit. Various liquid coolant systems have been devised in attempts to prevent mill and drill bits from becoming dull rapidly. In conventional practice the bit of a drill or milling machine is cooled by merely spraying water from distance onto the rotating bit of the milling machine or drill. However, in actuality very little cooling water reaches the tip of the bit and most of the water is thrown from the bit by centrifugal force and vertical drop of gravity. As a result, the milling machine or drill bit will typically overheat and become dull. Furthermore, chips of material which are cut from the metal stock tend to cling to a mill or drill bit, thereby increasing the heat generated. This reduces the quality of milling and also dulls the bit more rapidly.
A number of systems have also been proposed which involve the creation of internal channels within deep hole drilling bits. These internal channels lead to openings at the tip of the bit. Liquid coolant, such as water, is pumped through such bits and emerges from the bit tips at the metal cutting site. However, complex machining is involved in order to produce bits of such intricate construction. Such internally cooled bits are not commercially feasible, since their production cost far exceeds the cost of conventional bits. Any increase in useful life of such intricate bits is more than offset by the cost of manufacture of such devices. In addition, the creation of internal channels within a bit is impossible with bits of very small diameter. Furthermore, the creation of internal channels within a bit inherently weakens the bit. A bit with internal passages is far more likely to break than a solid bit. Moreover, the problem is increased several orders of magnitude when end mills are provided with internal passages. While a drill bit is subjected primarily an end loading, an end mill is subjected primarily to a side load which acts perpendicular to the weakened length of a bit having internal, liquid conduits.